2008 DODGE RAM 2500 DIESEL cooling

9. Oil Pressure Gauge
The pointer should always indicate some oil pres-
sure when the engine is running. A continuous
high or low reading, under normal driving conditions,
may indicate a lubrication system malfunction. Immedi-
ate service should be obtained.
NOTE:If the gauge pointer moves to either extreme of
the gauge, the ªCheck Gaugesº indicator will illuminate
and a single chime will sound.
10. Transfer Case Position
This display indicator shows the transfer case position
selection.
For additional information refer to ªFour-Wheel Drive
Operationº in Section 5 of this manual.11 .TOW HAUL
The TOW HAUL button is located at the end of the gear
shift lever. This light will illuminate when the TOW
HAUL button is pushed once.
12. Temperature Gauge
The temperature gauge indicates engine coolant
temperature. Any reading within the normal
range indicates that the cooling system is operat-
ing satisfactorily. The gauge needle will likely indicate a
higher temperature when driving in hot weather, up
mountain grades, in heavy traffic, or when towing a
trailer. If the needle rises to the ª245ÉFº (118ÉC) mark,
stop the vehicle, shift into NEUTRAL, and increase the
engine idle speed for two to three minutes. If the tem-
perature reading does not return to normal, shut your
engine OFF and allow it to cool. Seek authorized service
immediately. Refer to ªCooling Systemº under ªMain-
taining Your Vehicleº in Section 7.
UNDERSTANDING YOUR INSTRUMENT PANEL 191
4

CAUTION!
Do not leave your vehicle unattended with the en-
gine running as you would not be able to react to the
temperature indicator if the engine overheats.
NOTE:Engine idle speed will automatically increase to
1000 rpm at elevated coolant temperatures to improve
engine cooling.
NOTE:If the gauge pointer moves to either extreme of
the gauge, the ªCheck Gaugesº indicator will illuminate
and a single chime will sound.
13. Security Light
The light will flash rapidly for approximately 16 seconds
when the Vehicle Theft Alarm is arming. The light willflash at a slower rate after the alarm is set. The Security
Light will also come on for about two seconds when the
ignition is first turned ON.
14. Transmission Range Indicator (Automatic
Transmissions Only)
When the gear selector lever is moved on vehicles with
the 68RFE transmission, this indicator shows the auto-
matic transmission gear range selected (P R N D). Ve-
hicles equipped with Auto-6/Electronic Range Select
(ERS) will display the selection of the desired top gear, in
the position next to the D (Drive).
15. Odometer/Trip Odometer
The odometer shows the total distance the vehicle has
been driven. U.S. federal regulations require that upon
transfer of vehicle ownership, the seller certify to the
purchaser the correct mileage that the vehicle has been
driven. Therefore, if the odometer reading is changed
192 UNDERSTANDING YOUR INSTRUMENT PANEL

NOTE:To improve your selection choices, the system
allows you to operate at intermediate positions between
the major modes. These intermediate positions are iden-
tified by the small dots.
Recirculation Modes (Panel or Bi-Level)
Select the recirculation modes when
the outside air contains smoke, odors,
high humidity, or if rapid cooling is
desired. This feature allows for recir-
culation of interior air only. Air flows
through the panel only, or through
both the panel and floor vents depend-
ing on the selected mode (panel vs
bi-level).
NOTE:Selecting a Recirculation Mode does not neces-
sarily consume more fuel than normal A/C mode.
Panel
Outside air flows through the outlets located in the
instrument panel.
Bi-Level
Outside air flows through the outlets located in the
instrument panel and at the floor.
Floor
Outside air flows primarily through the floor out-
lets located under the instrument panel.
Mix
Outside air flows in equal proportions through the
floor and defroster outlets, and the air conditioning
may be on.
Defrost
Outside air is primarily directed to the windshield
through the defroster outlets located at the base of
UNDERSTANDING YOUR INSTRUMENT PANEL 253
4

Summer Operation
Air conditioned vehicles must be protected with a high
quality antifreeze coolant during summer to provide
proper corrosion protection and to raise the boiling point
of the coolant for protection against overheating. A 50 %
concentration is recommended. For proper coolant type,
refer to ªRecommended Fluids and Genuine Partsº in
Section 7.
When using the air conditioner in extremely heavy traffic
in hot weather, especially when towing a trailer, addi-
tional engine cooling may be required. If this situation is
encountered, operate the transmission in a lower gear to
increase engine RPM, coolant flow and fan speed. When
stopped in heavy traffic, it may be necessary to shift into
NEUTRAL and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.NOTE:On models equipped with Diesel engines, the
idle speed will automatically increase to 1000 rpm at
elevated coolant temperatures to improve engine cooling.
Your air conditioning system is also equipped with an
automatic recirculation system. When the system senses
a heavy load or high heat conditions, it may use partial
Recirculation A/C mode to provide additional comfort.
Winter Operation
When operating the system during the Winter months,
make sure the air intake, located directly in front of the
windshield, is free of ice, slush, snow, or other obstruc-
tions.
UNDERSTANDING YOUR INSTRUMENT PANEL 261
4

STARTING AND OPERATING
CONTENTS
mStarting Procedures ± Diesel Engines.........268
NAutomatic Transmission ± If Equipped......268
NManual Transmission ± If Equipped........269
NNormal Starting Procedure ± Engine Manifold
Air Temperature Above 66ÉF (19ÉC)........269
NStarting Procedure ± Engine Manifold Air
Temperature Below 66ÉF (19ÉC)...........270
NStarting Fluids.......................274
mNormal Operation (Diesel Engine)...........274
NCold Weather Precautions...............275NEngine Idling........................278
NStopping The Engine...................280
NEngine Speed Control..................281
NOperating Precautions..................281
NCooling System Tips Ð Automatic
Transmission........................281
mDiesel Exhaust Brake (Engine Braking) ±
If Equipped...........................283
mTransmission Shifting....................285
NAutomatic Transmission With Overdrive
(68RFE) Ð If Equipped.................285
5

Block Heater Usage
A.Temperatures below 0ÉF (-18ÉC)
²Block Heater Required for 15W-40
²Block Heater Recommended for 5W-40
B.Temperatures below - 20ÉF (-29ÉC)
²Block Heater Required for 5W-40
Winter Front Usage
If a winter front or cold weather cover is to be used, a
percentage of the total grille opening area must be left
uncovered to provide sufficient air flow to the charge air
cooler and automatic transmission oil cooler. The per-
centage of opening must be increased with the increasing
ambient air temperature and/or engine load. If the
cooling fan can be heard cycling frequently, increase the
size of the opening in the winter front. A suitable cold
weather cover is available from your Mopartdealer.
Battery Blanket Usage
A battery loses 60% of its cranking power as the battery
temperature decreases to 0ÉF (-18É). For the same de-
crease in temperature, the engine requires twice as much
power to crank at the same RPM. The use of 120 VAC
powered battery blankets will greatly increase starting
capability at low temperatures. Suitable battery blankets
are available from your authorized Mopartdealer.
Arctic Operation
Where there are no provisions to keep the engine warm
when it is operating in ambient temperatures consistently
below (-10ÉF/-23ÉC), use 5W-40syntheticengine oil and
fuel that meets the requirements in Section 7, ªMainte-
nance Procedures,º Engine Oil Selection.
Engine Warm-Up
Avoid full throttle operation when the engine is cold.
When starting a cold engine, bring the engine up to
operating speed slowly to allow the oil pressure to
stabilize as the engine warms up.
STARTING AND OPERATING 277
5

Engine Speed Control
CAUTION!
Prevent overspeeding the engine going down hill.
When descending steep grades, use a combination of
gears and service brakes to control vehicle/engine
speed. Overspeed can cause severe engine damage.
Operating Precautions
Avoid Overheating The Engine
The temperature of the coolant (a mixture of 50%
ethylene-glycol and 50% water) must not exceed the
normal range of the temperature gauge (240ÉF/116ÉC)
with a 16 psi (110 kPa) radiator cap.
Usually the coolant temperature indicated during opera-
tion will be to the left of center in the normal range of the
gauge.
Avoid Low Coolant Temperature Operation
Continual operation at low coolant temperature below
the normal range on the gauge (140ÉF/60ÉC) can be
harmful to the engine. Low coolant temperature can
cause incomplete combustion which allows carbon and
varnish to form on piston rings and injector nozzles.
Also, the unburned fuel can enter the crankcase, diluting
the lubricating oil and causing rapid wear to the engine.
Cooling System Tips Ð Automatic Transmission
To reduce potential for engine and transmission over-
heating in high ambient temperature conditions, take the
following actions:
²City Driving Ð
when stopped, put transmission in neutral and increase
engine idle speed.
²Highway Driving Ð
reduce your speed.
STARTING AND OPERATING 281
5

Upshifts into both overdrive gears, 5th and 6th, will be
delayed when the transmission fluid temperature is
below 40É F (4.5É C) or above 240É F (115.5É C).
NOTE:Use caution when operating a heavily loaded
vehicle in 2nd or 1st gear in high ambients as torque
converter slip can impose significant additional heat load
on the cooling system.
WARNING!
Never use Park position on an automatic transmis-
sion as a substitute for the parking brake. Always
apply parking brake fully when parked to guard
against vehicle movement and possible injury or
damage.
Overdrive Operation
The overdrive automatic transmission contains an elec-
tronically controlled 5th and 6th (Overdrive). The trans-
mission will automatically shift from Drive to Overdrive
if the following conditions are present:
²the transmission selector is in DRIVE;
²the engine coolant has reached normal operating tem-
perature;
²vehicle speed is above approximately 30 mph (48
km/h);
²the ªTOW HAUL O/D OFFº switch has not been
activated;
²transmission has reached normal operating tempera-
ture.
STARTING AND OPERATING 287
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